Fractionating columns



Oct. 11, 1955 L. s. TWOMEY ET AL FRACTIONATING COLUMNS 3 Sheets-Sheet 1 Filed Sept. 28, 1945 ENTORS LEE 5. TWOMEY j 3 ARFNCE J.SCHILLING ATTORNEY F IG r is w 1955 L. s. TWOMEY ETAL 2,720,389

' FRACTIONATING counvms Filed Sept. 28, 1945 3 Sheets-Sheet 2 FIG.8

LEE 5, TWOMEY CLAREN CE J. SCHILL ING mv5-roes ywlw.

A TTOPNEY 1955 L. s. TWOMEY ET AL 2,720,389

FRACTIONATING COLUMNS Filed Sept. 28, 1945 s Sheets-Sheet s mas/x LEE 5. TWOMEY C LARENCE J. SCHILLING INVENTORS United States Patent Office 2,720,389 Patented Oct. 11, 1955 FRACTIONATIN G COLUMNS Lee S. Twomey, Vista, Calif., and Clarence J. Schilling,

Chattanooga, Tenn., assignors to Air Products, Incorporated, Chattanooga, Tenn, a corporation of Michigan Application September 28, 1945, Serial No. 619,110 9 Claims. (Cl. 261-114) This invention relates generally to the fractionation of vaporizable liquids and specifically to the art of fractionating liquid air or other liquefied mixed gases.

An objective of the invention is to provide a fractionating column which will operate efficiently when its constituent plates are out of level.

An objective of the invention is to provide a fractionating column which will function in an etiicient manner when subjected to a rocking motion, as when mounted in a seagoing vessel.

An objective of the invention is to provide a large fractionating column, having widely extended plates, which is free from difficulties attendant on distribution of the liquid over the plate area.

An objective of the invention is to provide a novel form of bubbling, gas-liquid contacting unit of extreme efiiciency in the fractionation of liquefied gases.

An objective of the invention is to provide a fractionating column through which a plurality of streams of the liquid to be fractionated are caused to remain segregated in their fiow from plate to plate and are individually and repeatedly contacted with counterflowing vapors drawn from repeatedly intermixed vapor bodies.

An objective of the invention is to provide a simple and effective means for subdividing a single stream of a liquid into a plurality of streams of equal volume or of predetermined volumetric relation, and in which the divided or lesser streams will maintain a constant volumetric relation regardless of variations in the volume of the supplying stream.

Modern liquid fractionation is performed, almost without exception, in bubble plate columns. In their conventional form, these columns flow the reflux liquid across the plate and around all the bubble caps fixed in it. In columns even of small diameter and having a correspondingly small number of caps per plate, much difiiculty is experienced in producing even flow and distribution of the reflux liquid, without which the highest efiiciency cannot be attained. As the diameter of the plate increases the efficiency of the plate tends to decrease, by reason of poorer liquid distribution over its area. If for any reason, as for example buckling of the plate or settling of the column, the plate departs appreciably from a horizontal plane, its efficiency falls oif very rapidly and the plate becomes nonfunctional when the departure from horizontality is only a few degrees. I

Further, in very large columns the plates usually employed have an efiiciency somewhat lower than those in smaller units, because of the hydraulic gradient needed to cause the liquid to flow at the necessary velocity across a wide plate. This results in a liquid depth disadvantageously greater at the upstream than at the downstream edge of the plate. Through the employment of the invention herein described the plate may be divided into a number of sections, as regards liquid flow, of such dimensions as in large measure to avoid differences in depth and the resultant lowering of efficiency, avoiding the necessity for constructing a number of smaller complete columns.

Portable air fractionating plants are coming into extensive use for the manufacture of oxygen. In one application of these plants they are assembled on trucks or trailers which are moved from place to place as needed. The conventional bubble plate column, even when of small diameter, can be used in such plants only after tedious levelling of the truck bed each time the plant is moved.

In another and increasingly important application these plants are used on shipboard, a location in which the column is rocked by the motion of the vessel. The bubble plate columns of the prior art have proven to be completely useless for this purpose and the provision of bafiles or other means to minimize sloshing of the liquid has been shown to be ineffective.

The improvements herein described produce a column having an effectiveness equal to or greater than that of the conventional column operating under the most favorable conditions; which maintains its full fractionating efficiency when the column is set as much as 15 out of plumb or is rocked through a 30 are; which is not reduced in efiiciency by settling of the column or springing of the plates, and in which the plates may be made in any desired diameter without reduction in effectiveness. Thus the invention produces a column which may be used on trucks and trailers without relevelling and which may be operated on shipboard even during heavy weather. The novel features shown are also particularly adapted to the construction of columns having plates of great diameter, even when permanently installed in a fixed position and location.

The invention comprises a novel form of fractionating column proper in which the plates are provided with a plurality or multiplicity of pockets or wells, each feeding reflux liquid without redistribution into a well in the plate next below, in combination with a novel and effective means for distributing the liquid feed or supply stream among the wells on the uppermost plate and with certain accessories which tend to maintain the desired distribution unimpaired and which permit the distributing device to be flushed out with only a momentary interruption to the functioning of the column.

The invention will best be understood with reference to the attached drawings and the following description thereof, in which Fig. l is a vertical section through a single-stage air fractionating column embodying the basic features of the invention;

Fig. 2 is a plan section through the upper end of the column, as on the line 22 of Fig. 1;

Fig. 3 is a plan section through the column at the level indicated at 3--3 of Fig. 1;

Fig. 4 is a plan section through the column at the level indicated at 44 of Fig. 1;

Fig. 5 is a horizontal section, on an enlarged scale, of one form of the bubbling well indicated at 34 in Fig. 1 taken on the line 55 of Fig. 7;

Fig. 6 is a cross-section through the well as on the line 66 of Fig. 5;

Fig. 7 is a longitudinal section through the well as on the line 7-7 of Fig. 5;

Fig. 8 is a similar section on the line 88 of Fig. 5;

Fig. 9 is an outline diagram of a two-stage column in which the invention may be utilized, this figure illustrating the merger and redistribution of segregated liquid streams;

Fig. 10 is a vertical section through a modified form of inserted bubbling well, the drainage tubes being shown in elevation;

Fig. 11 is a cross-section through the well of Fig. 10 and 3 also through the well of Fig. 12, as on the line 11-11 of each of these figures;

Fig. 12 is a vertical section similar to that of Fig. 10, illustrating another modified form of inserted well;

Fig. 13 is a plan view of a fractionating plate on which the bubbling wells are formed by upwardly projected partitions;

Fig. 14 is a fragmental section through the plate as on the line 14-14 of Fig. 13;

Fig. 15 is a plan view of a modified form of the plate of Fig. 13, in which each well is provided with a plurality of bubble caps, and

Fig. 16 is a fragmental section as on the line 16-16 of Fig. 15.

Referring first to Fig. 1: The invention is illustrated in this figure as applied to a single-stage fractionating column, such as is often used in the fractionation of liquid air. This column consists of three functionally distinct sections: the distributing section A, the fractionating section B and the reboiling section C. The invention resides in the distributing section and in the structure and arrangement of plates in the fractionating section, the reboiling section being conventional.

Air previously compressed, dried and precooled by means not shown is introduced at 15 into a boiling coil 16 immersed in a bath 17 of liquid oxygen. In this coil the air is liquefied in supplying heat to the oxygen bath which is thus continuously boiled. The liquid air then passes through a conduit 18 and an expansion valve 19 by which it is brought to a lower pressure. The expanded liquid, together with any vapor evolved due to pressure reduction, are introduced into the upper end of the column as at 20, the liquid descending over and through the plates in a manner to be described. The vapor flashed off by pressure reduction, together with that separated by fractionation on the plates, escapes from the upper end of the column as at 20this is a nitrogen-rich vapor usually referred to as gaseous nitrogen, though it is never entirely pure. The oxygen separated by the plates in a desired purity and usually referred to as product oxygen is withdrawn from the lower end of the column, either as a liquid at 21A or as a vapor at 21B, as may be preferred. To this point the structure and steps described are well known and are no part of the instant invention.

The liquid entering the column at 20, being liquid air enriched in oxygen, descends over a funnel-shaped member 22 into an annular feed well 23, formed by concentric spacing of a feed tube 24 and a nitrogen vent tube 25. The feed tube is provided with a lower ring of metering perforations 26 and with an upper ring of overflow perforations 27. The size of the metering perforations is so adjusted (in the construction of the apparatus) that the liquid level 28 will lie below perforations 27 during normal operation, these openings being provided as a spillway in the event of flooding of the feed tube. The number of openings 27 is immaterial and one will suffice if of sufficient area to care for the maximum flow. It is preferable that the liquid level should lie above the meter ing perforations with the feed stream at normal size.

The liquids flowing through the individual perforations 26 of the lower ring pass into corresponding compartments .29 formed by the insertion of partitions 40 in a ring-shaped tray 30. Each of these compartments is provided with a drain tube 33 extending into one of the bubbling wells 34 in the uppermost fractionating plate 35A. The tray is illustrated as attached both to the feed tube and to the inner wall 31 of column shell 32, and the drain tubes are illustrated as scaling in liquid in the bubbling wells. Both of these arrangements are matters of convenience only, as the tray may be supported in any desired manner and the drain tubes may if preferred be provided with individual sealing cups or even left unsealed.

The structure just described will divide a liquid feed stream (using that word in the sense of any stream which is fed onto a fractionating plate, regardless of its origin) into any desired number of individual or lesser streams which will have a substantially constant volumetric relation. Ordinarily the perforations will have the same net area and will deliver substantially equal streams. By reason of the relatively small diameter of the liquid column in the feed tube, the hydraulic head on perforations occurring on opposite sides of the tube differs only very slightly even when the column is inclined. It is possible and might under some circumstances be advantageous to give the perforations different net areas to supply streams of different volumes, the volumetric relationship of which would be constant.

It has been found that small orifices, such as those indicated at 26, are liable to reduction in area or to stoppage by accumulation of ice crystals (for example, of water or carbon dioxide), particularly if the arrangements for caustic washing and drying of the air supply are not fully effective. The supply stream may also contain foreign matter such as pipe scale, metallic oxides, etc., which tend to restrict or to bridge the perforations and throw the distribution out of balance. If this condition is anticipated, it is desirable to place a fine screen 36 over the top of funnel 22 to stop the larger particles.

As a further precaution, such fine sediments as may pass the screen and tend to accumulate in the perforations may be dislodged and carried through by vibrating or reciprocating a solid body within the orifice. Fig. 1 shows an arrangement for this purpose which is adapted to use in truck-mounted or shipboard columns which, in their use, are subjected to vibration or oscillation. This device consists of a number of wires, preferably resilient, projected through the perforations from a suspended ring 38. This ring is swingingly supported from funnel 22 or feed tube 24 by light rods 39 which may well be looped at their ends. The wires are of less diameter than the perforation and remain within it, and are considered in figuring the net area of the remaining annular orifice.

The vibration of apparatus mounted on a truck or the swaying motion to which a shipboard column is subject cause ring 38 to swing through small arcs and the wires to vibrate and also to reciprocate through short distances, keeping the orifices free from sediments. The wires are also subjected to vibration by the flow of liquid around them. In the case of stationary columns, not subject to movement due to transportation or water support, a similar arrangement may be used if mechanical provision is made for imparting a vibratory or oscillatory movement to the ring by power or by the hand of the operator through a suitable seal. Or a solid body may be passed through and withdrawn from each orifice at intervals.

Considering now the relationship of the various plates and wells and referring again to Fig. l, the basic con-, cept in the invention is to divide each fractionating plate into a plurality of compartments or wells noncommunicating as to liquid, each provided with means for brin ing upflowing vapor into finely divided contact with liquid entering from a well above (or initially from the distributor) and draining into a well below or, in the case of the lowermost plate of a series, into a common pool or receptacle.

The showing in Fig. 1 of a distributor with a small number of metering orifices and tray compartments is for simplicity only and is not intended as suggesting an actual number to be used. In practice any number, greater or less than that shown, may be used, depending on column size and other design requirements.

The simplest and in many ways the most desirable application of this concept is-that in which a series of plates, extending through the entire length of the column or to a level at which redistribution becomes necessary, has the same number of wells per plate, in which the Wells in any one plate are of the same size, and in which each vertical series of wells is fed by the stream from a single orifice of the distributor and the stream passes down from well to well without intermixture.

This application of the theory of the invention is shown in Fig. 1, in which the stream from a single compartment of tray 30 passes through drain pipe 33A into a well 34 on the uppermost plate 35A and this well drains through tube 33B into a well on the next lower plate, this procedure being repeated until the less volatile fraction from each series of wells is merged in pool 17. The vapor streams passing through the wells (see Figs. 5 to 8 and to 16) are merged in the spaces between the plates and automatically redistributed in passing through the next higher plate. Thus segregated liquid streams are repeatedly contacted with upflowing and repeatedly redistributed vapor streams in their passage from a point of distribution to a point of collection.

Obviously this simple and wholly logical structure may be departed from in various ways, most of which would be pointless but would still leave many of the advantages of the invention. Thus, for example, the number of distributing orifices could be greater than the number of wells on the top plate, two or more of the streams being fed into a single well. The streams from two or more wells on one plate could be merged and fed into a single well of proportionately greater capacity on the next lower plate. One or more of the vertical series of wells may be of different capacity from the remainder of the series. These and similar hybrid structures are more diflicult to design and to fabricate than the simpler structure of the figure, but as they would retain many of the advantages inherent in the invention they are considered to be within its scope.

Under some circumstances, notably where a side stream enters the column, it is necessary to merge all of the segregated streams and to redistribute the merged stream. This situation is illustrated in Fig. 9, showing a twostage column. As is conventional in columns of this type, high-pressure nitrogen, liquefied by the reboiling condenser 52, is passed to the upper end of the column and onto a distributor A1 by which it is divided among the wells on the uppermost plate of low-pressure fractionating section B1.

The runbacks from the wells on the lowermost plate of this section are merged in a liquid pool which is illustrated as collected on a blind plate 53 having an opening surrounded by a dam 54 through which vapor passes upwardly and the merged stream flows downwardly onto a second distributor A2 which also received the side stream of crude oxygen passing up through conduit 55 from the base of the tower. The purpose of the pool is solely to seal the drain tubes from the plate above, which may be individually sealed if preferred. By the second distributor A2 the mixed stream of runback and side feed is divided among the wells on the uppermost plate in fractionating section B2.

The liquid nitrogen produced by the reboiling condenser is in part collected on a tray 56 from which the nitrogen stream above described is carried through conduit 57 to the upper end of the column. The excess over the quantity required to reflux the low-pressure plates overflows onto a distributor A3 by which it is divided among the wells on the uppermost plate of high-pressure fractionating section B3. The lowermost plate of this section drains into the pool 17 of crude oxygen in the base of the column. Compressed and cooled air is introduced into the column at 58, product oxygen is removed at 59 and gaseous nitrogen at 60, all in the customary manner.

. It may be observed that, in either the single or the double column, it is permissible though not the best practice to use conventional plates in one or more sections of a column while using plates constructed in ac- 6 cordance with the inventionin another section or sections.

The bubbling wells themselves may be constructed in various ways. Thus they may be formed as individual units, fixed in openings through the plates and depending beneath it as in Figs. 5-8 and 10-12. Or they may be formed on top of the plate, by partitions high enough to prevent horizontal flow of liquid, each well thus formed being provided with one or more bubble caps of conventional pattern, as in Figs. 13-16. The selection of a form will depend on the size of the column and the use to which it is put, and on individual preference.

Referring first to Figs. 5, 6, 7 and 8, which illustrate a form particularly adapted to use in a shipboard oxygen column, a more or less rectangular cup 61 is formed of sheet metal, plastic or other material adapted to temperature conditions and the nature of the fluids within the column. This cup is provided with one or more partition plates or septa 62 which are joined to the outer walls 63 in such manner as to form an upwardly open compartment 64 and one or more upwardly closed compartments 65. The outer wall is provided with openings 66 at a level not far below the lower face of the plate in which the cup is inserted.

The septum is provided along its lower edge with slots or serrations 67, which may be replaced by a row of small holes or other perforations. A tube 33A depends into the open compartment, from the distributor in the case of the topmost plate of a section, or from a cup in an overlying plate. A tube 33B is sealed in the bottom of the cup and conducts overflowing liquid into the cup next below, in which it becomes tube 33A. This tube acts as a dam to maintain the upper ends of the serrations, or the equivalent perforations, substantially submerged in liquid pool 68 at all times.

if the column is to be subjected to a rocking motion, as in a shipboard column, the depth of pool 68 should be so proportioned to the height of the serrations and the dimensions of the cup that adequate submergence will be maintained at the maximum inclination to which the column is subjected while in operation. It is also desirable in the use of cups having unequal horizontal dimensions to orient the column in such manner that the longer axes of the cups will be directed fore and aft of the vessel, that being the direction in which the rocking motion and the consequent angle of inclination is ordinarily least.

When a cup so constructed is passed through and sealed into a horizontal partition plate, as for example plate 35B of Fig. 1, vapor moving upwardly through the column enters the closed compartment 65 through openings 66 from the space 69A below the plate. The vapor depresses the liquid level in this compartment sufficiently to escape through perforations 67 into open compartmerit 64, in which it bubbles through the liquid in pool 68 and escapes into space 693 above the plate. The liquid flowing into the open compartment through tube 33A overflows through tube 338 (as shown in Fig. 7) into the open compartment in one cup on the plate next below, there being no liquid communication between the cups on any one plate. The upflowing vapor is divided into individual streams only in passing through the plates and is merged in the space between each pair of plates to be redistributed in passing through the plate next above.

The cups may be fixed in the plate at their upper edges, as illustrated, or may project for some distance above the plate, but in all cases the openings 66 in the side wall must lie beneath the lower surface of the plate in which the cup is fixed.

The modified form of cup illustrated in Figs. 10 and 11 functions in the same manner as above: described and difiers from the rectangular cup mainly in contour. In this form the outer wall 63 of the cup may be a short piece of round or oval tubing or it may be a spun or stamped unit. The septum is a smaller tube flanged at its upper edge, the closed compartment thus being annular. The septum may be serrated along its lower edge, as in Fig. 7, or it may have a ring of small holes as at 69 in Fig. 10.

In the slightly modified form shown in Figs. 11 and 12, a cup 70 is afiixed to the lower end of a tube 71. At its lower end the tube is perforated or slotted as at 72, the upper end of the tube being fixed in plate 35, as for example by expanding. The cup 70 is enough shorter than the tube toleave an annular opening 73 below plate 35 for the entrance of vapor, which passes through slots 72 and into the tube, from which it escapes into the space above the plate. This combination produces an outer compartment 74' in communication with the space below the plate and an inner compartment 74 in communication above the plate. This form is useful in both small and large towers because of the ease with which it may be constructed and positioned in the plate.

In the construction of large columns it may be convenient or economical to form the bubbling wells above the plates rather than as units depending beneath it, such forms being illustrated in Figs. 13 to 16 inclusive.

Referring first to Figs. 13 and 14, plate 35 is provided with upwardly projecting partitions nonleakably joined to the plate and to each other to form a plurality of bubbling wells 76. Each well is provided with a bubble cap 77, which may be of any conventional or preferred form. The drain tubes 33A depend into the well from a well in the plate above and tubes 33B pass through the bottom of the Well into a well on the plate next below.

Figs. 15 and 16 show the same arrangement of wells and bubble caps except that each well 76 contains a plurality of caps 77. If four or more caps are placed in a single compartment it is desirable to place a baffle or baffies, as for example at 78, to prevent liquid from flowing directly across the bottom of the well.

All the forms of plate shown have the common advantages of avoiding difiiculties incident to distribution of reflux liquid over the conventional plate and of remaining functional when out of a horizontal plane or when subjected to movement. In conjunction with a distributing means they provide a column which will show the highest operating efficiency even under adverse conditions.

We claim:

1. In a liquid fractionating column: means for dividing a liquid stream into a plurality of lesser streams of predetermined substantially constant volumetric relation; a vertical succession of fractionating plates having each a plurality of bubbling wells opening upwardly into a common vapor collecting space; the bubbling wells being arranged on each of the plates with at least two bubbling wells lying on a straight line extending from the center of the plate to its periphery in each quadrant of the plate; each bubbling well having an area constituting a minor fraction of the area of a quadrant; means for conducting each of said lesser streams into one of the wells in the uppermost plate in said succession; means for conducting the lesser liquid stream from each well in each plate except the lowermost in said succession into a single and different well in the plate next below; means located at a medial point in said vertical succession for merging and intermixing said lesser streams; means supplied at least in part with liquid by said merging means for redividing said merged liquid to supply segregated liquid streams to the plates located therebelow, and means for passing vapor upwardly through the bubbling wells in said plates and through said common vapor collecting spaces.

2. In a liquid fractionating column: means for dividing a liquid stream into a plurality of lesser streams of predetermined substantially constant volumetric relation; a first series of fractionating plates each provided with a number of bubbling wells equal to the number of said lesser streams; means for the downward passage of each of said lesser streams from one well in one plate to one well in the plate next below; means below said first series of plates for merging said lesser streams; means for redividing the merged liquid into a plurality of segregated liquid streams; a second series of fractionating plates each provided with a number of bubbling wells equal to the number of said segregated streams; means for the downward passage of said segregated streams from one well in one plate to one well in the plate next below; means for producing an upfiow of vapor through said column in counterflow contact with the liquid streams flowing through said wells, and means for merging the vapor streams flowing through all the bubbling wells on each individual plate, the bubbling wells in the first and second series of plates being arranged on the plates with at least two bubbling wells lying on a straight line extending from the center of the plate to its periphery in each quadrant of the plate and each of the bubbling wells having an area constituting a minor fraction of the area of a quadrant.

3. In a fractionating column: a vertical succession of plates horizontally disposed in said column and extending across its area; a plurality of liquid-receiving wells disposed over the area of each said plate, said wells being so formed as to prevent the flow of liquid from one well to another without obstructing the movement of vapor over the upper surface of said plate; the liquidreceiving wells being disposed on each of the plates with at least two wells lying on a straight line extending from the center of the plate to its periphery in each quadrant of the plate, each well having an area constituting a minor fraction of the area of a quadrant; each of the wells including a dividing wall arranged to form two horizontally adjacent compartments in the well, means to admit a fiow of vapor into the upper part of one of said compartments, foraminous means located in said dividing Wall to permit a flow of vapor from said one compartment into the other of said compartments, means for permitting a fiow of vapor from said other compartment to the unobstructed space above the associated plate, means for introducing a flow of liquid into said compartments and overflow means arranged to drain liquid from said compartments while maintaining the exits of said foraminous means substantially submerged in liquid.

4. In a fractionating column positioned in a marine vessel, a fractionating tray having a plurality of liquidvapor contacting compartments, each compartment be ing provided with two substantially parallel partitions, each partition being provided with a horizontal row of vapor orifices, the row length being greater than the distance between said partitions, the partitions in the plurality of compartments being parallel with each other, the tray being so oriented that the rows of orifices are directed substantially fore and aft of said vessel, and means for preventing mingling of the liquids between compartments. 7

5. In a fractionating column, comprising: a plurality of vertically spaced trays extending across the column, a plurality of bubbling wells disposed over the area of each tray, the remaining area of each tray being vapor and liquid impervious, the bubbling wells being arranged on each of the trays with at least two bubbling wells lying on a straight line extending from the center of the tray to its periphery in each quadrant of the tray, each bubbling well having an area constituting a minor fraction of the area of a quadrant, each bubbling well including a cup affixed in an opening in the associated tray, the upper edge of said cup being spaced from the next higher tray in said column, a septum dividing said cup into a first compartment and a second compartment, means for the passage of vapor from the space beneath said tray into the upper portion of said first compartment, means for the passage of vapor in small streams through the lower portion of said septum into said second compartment and thence to the space above said tray, a dam arranged in the second compartment for maintaining a pool of liquid within said second compartment and means for draining excess liquid therefrom to a compartment on a tray below.

6. In a fractionating column so located as to be subjected to movement, comprising: a plurality of vertically spaced trays extending across the column, a plurality of bubbling wells disposed over the area of each tray, the remaining area of each tray being vapor and liquid impervious, each bubbling well including a cup aflixed to the associated tray, the upper edge of said cup being spaced from the next higher tray in said column, a septum dividing said cup into a first compartment and a second compartment, said septum having orifices in its lower portion to permit passage of vapor from said first to said second compartment, means for the passage of liquid into said second compartment, means for the passage of vapor from the space beneath said tray into the upper portion of said first compartment, means for draining excess liquid from said second compartment, and a dam arranged in said second compartment to retain a pool of liquid therein, the height of said dam being so related to the dimensions of said cup as to maintain said orifices substantially submerged in said liquid pool at the maximum angle of inclination to which said column and said cup are subjected while in operation.

7. In a fractionating column, comprising: a plurality of vertically spaced trays extending across the column, a plurality of bubbling wells disposed over the area of each tray, the remaining area of each tray being vapor and liquid impervious, the bubbling wells being arranged on each of the trays with at least two bubbling wells lying on a straight line extending from the center of the tray to its periphery in each quadrant of the tray, each bubbling well having an area constituting a minor fraction of the area of a quadrant, each bubbling Well including a cup affixed in the associated tray, said cup having one horizontal dimension materially exceeding the other, a septum longitudinally arranged within and dividing said cup into an upwardly closed compartment and an upwardly open compartment, means for the passage of vapor from the space below said tray into the upper portion of said closed compartment, means for the passage of vapor through the lower portion of said septum into said open compartment, a dam arranged in the open compartment for maintaining a pool of liquid within said open compartment and means for draining excess liquid therefrom to a compartment in a tray below.

8. Gas contact apparatus comprising a column, a plurality of vertically spaced trays extending across the column, a plurality of cups disposed over the area of each tray and afiixed to and depending from such tray, the remaining area of each tray being vapor and liquid impervious, each cup terminating upwardly at a level not substantially higher than the upper surface of said tray, a septum dividing each cup into a first compartment and a second compartment, said septum having openings along its lower edge to permit passage of vapor from said first to said second compartment, means for the passage of vapor from the space beneath said tray into the upper portion of said first compartment, means for draining excess liquid from said second compartment, and a dam arranged in said second compartment to retain a pool of liquid therein, the height of said dam being so related to the dimensions of said cup as to maintain said openings substantially submerged in said liquid pool.

9. Gasliquid contact apparatus comprising a column, a plurality of vertically spaced tray members extending across the column and partitioning the column vertically, open top compartments presented by the trays having bottom walls and side walls, the compartments being arranged on each of the trays with at least two compartments lying on a straight line extending from the center of the tray to its periphery in each quadrant of the tray, each compartment having an area constituting a minor fraction of the area of a quadrant, means in each compartment for forming a pool of liquid with the level of the liquid below the upper edges of the side Walls of the compartment, means above the uppermost tray for dividing liquid to be contacted into a plurality of component streams, a conduit for each component stream extending from the last claimed means downwardly into a single and different compartment in the uppermost tray, the outlet for each conduit being below the liquid level of the liquid in the associated compartment, conduit means connected to each compartment for conducting excess liquid from the compartment to a single and different compartment of the next tray below, the outlet for each last claimed conduit being below the liquid level of the compartment to which the liquid is conducted, gas passage means extending through a wall of each compartment to a point above the level of the liquid in the compartment, and outlet means for the gas passage means extending to a point below the liquid level of the pool in the associated compartment, whereby gas ascending the column will bubble through the liquid in each pool.

References Cited in the file of this patent UNITED STATES PATENTS 1,032,657 Briggs July 16, 1912 1,113,643 Jonas Oct. 13, 1914 1,418,885 Schulze June 6, 1922 1,467,583 Lichtenthaeler Sept. 11, 1923 1,502,573 Kuhn July 22, 1924 1,605,263 Millard Nov. 2, 1926 1,738,870 Cox et al. Dec. 10, 1929 1,857,816 Lichtenthaeler May 10, 1932 1,865,172 Cook June 28, 1932 1,948,500 Bielfeldt Feb. 27, 1934 2,020,751 West Nov. 12, 1935 2,051,545 Collins Aug. 18, 1936 2,202,071 Van Dongen et al May 28, 1940 2,249,846 Mojonnier July 22, 1941 2,253,925 Zimmerman Aug. 26, 1941 2,344,560 Palkin et al. Mar. 21, 1944 2,366,958 Dennis Jan. 9, 1945 2,376,341 Burk et a1 May 22, 1945 2,394,133 Zimmerman Feb. 5, 1946 

1. IN A LIQUID FRACTIONATING COLUMN: MEANS FOR DIVIDING A LIQUID STREAM INTO A PLURALITY OF LESSER STREAMS OF PREDETERMINED SUBSTANTIALLY CONSTANT VOLUMETRIC RELATION; A VERTICAL SUCCESSION OF FRACTIONATING PLATES HAVING EACH A PLURALITY OF BUBBLING WELLS OPENING UPWARDLY INTO A COMMON VAPOR COLLECTING SPACE; THE BUBBLING WELLS BEING ARRANGED ON EACH OF THE PLATES WITH AT LEAST TWO BUBBLING WELLS LYING ON A STRAIGHT LINE EXTENDING FROM THE CENTER OF THE PLATE TO ITS PERIPHERY IN EACH QUADRANT OF THE PLATE; EACH BUBBLING WELL HAVING AN AREA CONSTITUTING A MINOR FRACTION OF THE AREA OF A QUADRANT; MEANS FOR CONDUCTING EACH OF SAID LESSER STREAMS INTO ONE OF THE WELLS IN THE UPPERMOST PLATE IN SAID SUCCESSION; MEANS FOR CONDUCTING THE LESSER LIQUID STREAM FROM EACH WELL IN EACH PLATE EXCEPT THE LOWERMOST IN SAID SUCCESSION INTO A SINGLE AND DIFFERENT WELL IN THE PLATE NEXT BELOW; MEANS LOCATED AT A MEDIAL POINT IN SAID VERTICAL SUCCESSION FOR MERGING AND INTERMIXING SAID LESSER STREAMS; MEANS SUPPLIED AT LEAST IN PART WITH LIQUID BY SAID MERGING MEANS FOR REDIVIDING SAID MERGED LIQUID TO SUPPLY SEGREGATED LIQUID STREAMS TO THE PLATES LOCATED THEREBELOW, AND MEANS FOR PASSING VAPOR UPWARDLY THROUGH THE BUBBLING WELLS IN SAID PLATES AND THROUGH SAID COMMON VAPOR COLLECTING SPACES. 